I've owned the P5s and the Momentums. The P5s were indeed incredibly disappointing sound-wise. I liked the Momentum quite a bit, but my ears became very sore after even short listening sessions because of the small ear cups. Returned those for a pair of P7s, which I still have.

Sound-wise, they're on par with each other. Momentums have better vocals because of their emphasis on mids, while the P7s have something of a proper soundstage and can actually replicate the kind of sub-bass which you feel but not really hear.

In terms of comfort, P7s have a bit more clamp than the Momentums initially but that wears off and they're really comfy otherwise. Like you said, they're proper over-ear designs, and that really was the clinching factor for me. Aside from that, they're definitely not worth $150 more than the Momentums, but for me, I really had no choice between the two because of the comfort issues.

Oh, and I haven't done any critical listening on them, but you might want to try out the B&O H6 at your local Apple store. Those things are insanely comfy.

I picked up the P7s today, am going to order the NADs later this week. I can get slightly reduced pricing on both. I'm also contemplating ordering the KEF M500 today as KEF has them $50 off for memorial day. I'm going to waffle on the last one for a few as they do appear to have a restocking fee. Typically I don't like on-ears, but from what I've read they are very comfortable and I tried on a set of Klipsch Image Ones at Brookstone, which have a similar pad design, and they were very comfortable. I'm also a self admitted KEF fanboy.

In order to help those of us with larger ears, I have started a thread on cup sizes of portable circumarual headphones. All owners of cans in this MH thread are welcome to submit their data to help potential buyers.

I picked up the P7s today, am going to order the NADs later this week. I can get slightly reduced pricing on both. I'm also contemplating ordering the KEF M500 today as KEF has them $50 off for memorial day. I'm going to waffle on the last one for a few as they do appear to have a restocking fee. Typically I don't like on-ears, but from what I've read they are very comfortable and I tried on a set of Klipsch Image Ones at Brookstone, which have a similar pad design, and they were very comfortable. I'm also a self admitted KEF fanboy.

The P7s went back yesterday. I personally thought they sounded terrible. Bloated bass really altered mid-range for me. Female vocals on them were terrible. I ordered the NADs, and hopefully they will get here next this week or next. I also picked up some B&O H6 at the Apple Store today, and am listening to them while posting this. So far, yes they are a bit bass light, but not terrible. That said, they sound really really good so far. Much better than the P7s for sure. Much cleaner and no real coloring of the other ranges. They also have some decent imaging for a closed can. Looks like these will be doing battle against the NADs. Will be hard to ignore the price difference though for what I picked up the NADs for. That said, the B&Os are gorgeous (got the silver and tan version).

The P7s went back yesterday. I personally thought they sounded terrible. Bloated bass really altered mid-range for me. Female vocals on them were terrible. I ordered the NADs, and hopefully they will get here next this week or next. I also picked up some B&O H6 at the Apple Store today, and am listening to them while posting this. So far, yes they are a bit bass light, but not terrible. That said, they sound really really good so far. Much better than the P7s for sure. Much cleaner and no real coloring of the other ranges. They also have some decent imaging for a closed can. Looks like these will be doing battle against the NADs. Will be hard to ignore the price difference though for what I picked up the NADs for. That said, the B&Os are gorgeous (got the silver and tan version).

thats a great looking colour on dem cans! lol keep us posted! if i had to pick i would really just stick with the h6s the earpads on the nad is not bad but not where near as comfortable as the h6s plus the h6s look a lot better none of that square headband design!

wonder how the soundstage fairs on the nad. the h6s were pretty expansive for a closed can

Might I recommend the Fiio X3. It's a magical improvement, and even more so with the new 3.0 firmware.

Thanks for the recommendation, but I'm not a DAP kinda guy. Just more to carry...at least with the E11 and A200p, they are small and plug into either my iPhone or iPad (which are pretty much always with me when I travel).

thats a great looking colour on dem cans! lol keep us posted! if i had to pick i would really just stick with the h6s the earpads on the nad is not bad but not where near as comfortable as the h6s plus the h6s look a lot better none of that square headband design!

wonder how the soundstage fairs on the nad. the h6s were pretty expansive for a closed can

Will hopefully find out soon. The shipping on my NADs is taking longer than I care for. While an attractive set of headphones is nice, I can't personally see them when they're on my head so I'm not sure how much it matters. That and I already wear toe shoes on a pretty regular basis so people are usually staring at my feet rather than my head anyways. :) I mainly care about sound quality and comfort. That being said, I had the choice between the back on black H6 or the silver & tan. The choice was pretty clear.

Anyway, great review mate, very helpful! I definitely wasn't considering the T51p as my portable candidate, but now I am (especially considering they cost much less than the SRH1540). I always find on-ears to be uncomfortable, but it seems that you find the T51p to be very comfortable.